(1) Field of the Invention
This invention relates to antennas and, more particularly, to traveling wave antennas.
(2) Prior Art
The load termination for a traveling wavy array should absorb or radiate without reflecting all the energy incident upon the end of the array to avoid a large back lobe. Known prior art traveling wave arrays have utilized two kinds of load terminations: resistive and radiating. An internal nonradiating resistive termination absorbs all of the energy, typically about 10% of the total energy incident upon the end of the array, so that no reflected back lobe in the antenna pattern occurs. When a resistive termination is used, the efficiency of the array cannot exceed 90% because of the energy lost in the resistive load. Further, resistors for such terminations typically dissipate several to tens of watts or more power, and they require considerable space and care in mounting for thermal control.
On the other hand, prior art radiating load terminations dissipate all energy incident upon the end of the array in a direction or polarization other than the principal polarization and direction of the main beam of the array. Thus, prior art radiating load terminations do not contribute to the gain and efficiency of the traveling wave array. Radiating loads have been used on the back sides of traveling wave arrays. The radiation takes place on the inside of the cylinder into which the array is mounted and is wasted. These are some of the problems this invention overcomes.